Molded-case circuit breaker with manual tripping means externally accessible only by a tool



N 1969 B. w. LAYTON ETAL 3,480,890

MOLDED-CASE CIRCUIT BREAKER WITH MANUAL TRIPPING MEANS EXTERNALLY ACCESSIBLE ONLY BY A TOOL Filed March 26, 1968 v 2 SheetsSheet 1 A27 ?o4 39 M -45 72 I [/VVENTOR. 3 BERYL w. LA'YTO'N ROBERT w. DUNHAM .Efi

LAYTON ET AL MOLDED-CASE CIRCUIT BREAKER WITH MANUAL TRIPPING 2 Sheets-Sheet 2 Nov. 25, 1969 B. w.

MEANS EXTERNALLY ACCESSIBLE ONLY BY A TOOL Filed March 26, 1968 ,QN mm mm United States Patent MOLDED-CASE CIRCUIT BREAKER WITH MANUAL TRIPPING MEANS EXTERNALLY AOCESSIBLE ONLY BY A TOOL Beryl W. Layton and Robert W. Dunham, Cedar Rapids, Iowa, assignors to Square D Company, Park Ridge, Ill., a corporation of Michigan Filed Mar. 26, 1968, Ser. No. 716,210 Int. Cl, H01h 73/ 48 US. Cl. 335-23 3 Claims ABSTRACT OF THE DISCLOSURE A push-to-trip rod has its outer end face disposed within a relatively small opening extending through the case of the circuit breaker and is restrained for rectilinear motion by the wall of the case about the opening and by a bracket inside the case. The rod is biased outwardly by a helical spring. The inner end face of the rod, when the rod is moved inwardly by a tool received in the opening, engages a common trip bar to effect tripping of the circuit breaker.

This invention relates to molded-case circuit breakers, and more particularly to a molded-case circuit breaker having means for effecting tripping of the circuit breaker by a tool without opening the case.

' In applying molded-case circuit breakers, it is often necessary to trip them after final installation to be sure that their operating mechanisms are fully operative. For the smaller sizes of circuit breakers, this can be done by jarring the circuit breaker sufficiently to cause the latch to release the trip bar or, because of the small current required for tripping, by applying current to the trip mechanism to effect tripping in the normal manner. In recent years, molded-case circuit breakers of greatly increased current carrying capacity have become available with consequent increase in physical size and in the pressure between the latch and the trip lever. Further,

the larger circuit breakers are often mounted within en closures with electromagnetic motor starters, and the test of the operating mechanism should be made only after such installation is complete. Accordingly, jarring forces sufilcient to trip the circuit breaker are difficult to apply and when applied are apt to damage the circuit breaker case or other equipment adjacent to it, and because of the large current required to eifect tripping in the normal manner the use of current for test tripping is impractical. There thus has been a demand for molded-case circuit breakers which include a means operable to trip the circuit breaker without applying current or opening the case, but which means would not be apt to be used to trip the circuit breaker for other than test purposes.

It is known in the art to provide circuit breakers with manual tripping means exposed at the outside of the case of enclosure for convenient manual tripping. For example, in Goodwin Patent No. 3,072,768, issued Jan. 8, 1963, a rod having a head portion extending outside the enclosure of a metal-clad circuit breaker when depressed turns a trip shaft to trip the circuit breaker. In Piteo Patent No. 3,158,711, issued Nov. 24, 1964, a button outside of an enclosure of a circuit breaker may be depressed to move a shaft, extending from the button, into engagement with an extension of a latch to rotate the latch and effect tripping of the circuit breaker.

In Schultz Patent No. 3,188,416, issued June 8, 1965, a rod projecting outside the case of a circuit breaker is engaged by an electrical plug upon insertion of the plug into a receptacle adjacent the circuit breaker to trip the 3,480,890 Patented Nov. 25, 1969 ice circuit breaker thereby to ensure that the circuit through the circuit breaker is open when the plug makes electrical contact in the receptacle.

The above patents evidence that it is known heretofore to provide a means outside a circuit breakercase to trip the operating mechanism of the circuit breaker. However, such arrangements are not suitable for circuit breakers 'to be used in combination starters and for other applications where continuity of power is important because the prior tripping means are so exposed as to be subject to inadvertent operation or to frequent operation for other than test purposes.

However, it is new, and it is the principal feature of the present invention, to provide a multipole moldedcase circuit breaker each pole of which has its own automatic tripping mechanism, with a means accessible from outsidethe case only by a tool to effect tripping of all poles of the circuit breaker. Specifically, it is new to provide a molded-case circuit breaker with a rod having its end portion within an opening of small diameter extending through the case and its outer end face spaced inwardly from the outer surface of the case about the opening, the diameter of the opening and the distance from the outer surface of the case to the outer end of the rod being such that the rod cannot be operated by a human finger. The present invention is thus an improvement over the above patents in which the manuallyoperable non-electrical tripping means is arranged to be readily accessible from the outside of the case.

It is an object of this invention to provide a moldedcase circuit breaker having an improved manually-operable means for tripping the circuit breaker thereby to test the operating mechanism thereof.

Another object is to provide a molded-case circuit breaker having an improved manually-operable tripping means which can be operated without opening the circuit breaker case only by one of a pointed tool such as a screwdriver.

Further objects and advantages will become apparent from the following description wherein reference is made to the drawings, in which:

FIG. 1 is a top plan view of a multipole circuit break er provided with a manually-operable tripping means in accordance with this invention;

FIG. 2 is a fragmentary sectional view taken generally along the line 22 of FIG. 1;

FIG. 3 is a top view of an outer pole section of the circuit breaker of FIG. 1 with the cover removed, the outer pole section shown having the manually-operable tripping means;

FIG. 4 is a fragmentary sectional view taken generally along the line 44 of FIG. 1; and

FIG. 5 is a perspective view of the manually-operable tripping means shown in FIGS. 1, 2 and 3.

For exemplary purposes, the invention is shown and described with respect to a three-pole circuit breaker, although it will be obvious that the invention is equally applicable to circuit breakers of a different number of poles. The three-pole circuit breaker is of the type disclosed in Leonard Patent No. 3,341,791, issued Sept. 12, 1967, to which reference may be had for a detailed description, and includes a two-part case having a base 20 and a cover 21, and an operating handle 22, all preferably molded of an insulating material. The handle 22 has an inner arcuate shoulder portion 23, and the cover 22 has an opening 24 for receiving an outer end of the handle 22 and is provided with suitable on and off indicia. The handle 22 forms part of a handle arm assembly pivoted on a pin 25. The base 20 and cover 21 are preferably secured together by two pairs of rivets 26 disposed respectively adjacent opposite ends of the case in partition walls separating the three poles of the circuit breaker.

Each pole of the circuit breaker is provided at one end with an electrical connector 30 normally used as a line terminal and at the other end with a preferably identical electrical connector 32 normally used as a load terminal.

The base includes a bottom or rear wall portion 33 from which a pair of parallel outer side wall portions, such as the wall portion 34, and a pair of identical parallel-spaced inner wall portions, such as the wall portion 36, extend perpendicularly. The inner wall portions 36 separate the three poles of the circuit breaker but are upwardly recessed in two places for respectively receiving a common trip bar 39 and a contact arm crossbar 40 both of which extend transversely of the three poles. A pair of spaced fiberboard inserts or stops 41, only one of which is shown, limit opening movement of the crossbar 40. The opposite end portions of the wall portions 34 and 36 are thickened as shown in FIG. 2, the rivets 26 being received in the thickened portions of the inner wall portions 36.

Each pole of the circuit breaker includes a stationary contact 42, a contact arm 43 pivotally mounted adjacent one end, and a movable contact 44 carried adjacent the free end of the respective contact arm and engageable with its associated stationary contact 42. The contact arms 43 of the outer poles are pivoted on respective pins 45.

Each stationary contact 42 is secured to an inner end portion of a bronze line terminal strap 46 having one of the line terminals 30 secured to the outer end thereof. The line terminals 30 and load terminals 32 are constructed in accordance with Patent No. 3,187,299, issued June 1, 1965. The terminals respectively include rectangular aluminum body portions 48 (FIG. 2) which are respectively apertured endwise of the circuit breaker to receive aluminum or copper wires and are respectively provided with wire clamping screws 50.

The contacts 42-44 of each pole are provided with a suitable arc chute 61.

Each contact arm 43 of the outer poles is pivoted on one of the pins 45, which are held in place by retainers 62, and is resiliently secured to the crossbar 40 by means of a U-shaped spring 64 having a bight portion disposed in a suitable notch in the end of the respective contact arm 43 opposite from the respective contact 44. The leg portions of each spring 64 are disposed on opposite sides of the respective contact arm, the free end portions of the leg portions of each spring 64 being received and held in appropriate slots in the crossbar 40.

The pivoting of the common trip bar 39 clockwise as viewed in FIGS. 2 and 4 to trip the circuit breaker may be elfected thermally upon sustained moderate overloads or magnetically upon severe overloads. Thus, each pole of the circuit breaker is provided with a bronze load terminal strap 66 having an outer end portion clamped to one of the load terminals 32. The terminal straps 66 are constructed and arranged to extend from the respective load terminals 32 for a considerable distance along the bottom wall portion 33. Each pole is also provided with a bimetallic strip 68 secured adjacent an inner end (not shown) to the inner end portion of the respective terminal strap 66 and having a flexible conductor 70 secured thereto adjacent the other or outer end. The flexible conductors 70 serve to conduct current from the bimetallic strips 68 to the respective contact arms 43. Each bimetallic strip 68 slopes upwardly away from its associated terminal strap 66 and has its outer end portion positioned below one of three projecting lugs 72 formed on the common trip crossbar 39. Upon the occurrence of a sustained moderate overload current flow in any of the terminal straps 66, the respective bimetallic strip 68 deflects upwardly and engages its respective lug 72 and pivots the common trip bar 39 clockwise as viewed in FIGS. 2 and 4 to release a generally V-shaped intermediate latch member 74 (FIG. 4) to trip the circuit breaker as explained in the aforementioned Patent No. 3,341,791.

A trip lever 76 is releasably latched in the ON position of the circuit breaker by a double latching arrangement comprising a rotatable pin 78 fixedly secured to the latch member 74. The trip lever 76 is provided with an angularly extending tongue 82 engagea-ble with a latch surface 84 of the latch member 74, the latch surface 84 defining one edge of a slot 86 provided in the latch member 74. The latch member 74 is provided with a tongue 88 engageable with a latch surface provided by an edge of a latch plate 90 secured to the common trip bar 39. The trip lever 76 is biased counterclockwise to the latched position shown in FIG. 4 by a spring toggle mechanism (not shown) of the circuit breaker. When the common trip bar 39 is pivoted clockwise as viewed in FIG. 4, the latch surface of the latch plate 90 is pivoted from under the tongue 88 and the latch member 74 pivots clockwise to release the trip lever 76 which then pivots counterclockwise to a tripped position thereof. A spring 91 is provided to return the latch member 74 to its original position. The pivoting of the trip lever 76 to tripped position eflFects operation of the spring toggle mechanism of the circuit breaker causing the crossbar 40 to move the contact arms 43 of the three poles to the open or tripped position to separate the respective pairs of contacts 42 and 44. The spring toggle mechanism also causes the handle 22 to move to tripped position.

The handle 22 is operable to reset the circuit breaker, that is, to reclose the pairs of contacts 42 and 44 and to relatch the latch mechanism, and is also operable to effect opening and closing of the pairs of contacts 42 and 44 independently of the latch mechanism all as explained in Patent No. 3,341,791.

Each pole of the circuit breaker is provided with a stiff insulating barrier 92 adjacent the respective load terminals 32. A separate bracket is riveted or otherwise secured to the inner surface of the insulating barrier 92 of each pole. The brackets for the center pole and one of the outer poles are respectively like those shown for the center and outer poles in Patent No. 3,341,791, whereas a bracket 94 for the outer pole hereof is modified. A lower arm 96 of the bracket 94 extends perpendicular to its associated barrier 92 and is provided with two apertures one of which reciprocally receives an internally threaded sleeve 98 slotted at its upper end. Another of the apertures receives a hooked end of a tension spring 99.

The common trip bar 39 is normally biased in the counterclockwise direction as viewed in FIGS. 2, 4 and 5 by a pair of springs 100 formed from flat stock and respectively located in the two outer poles. One end of each spring 100 is anchored in the respective barrier 92, and the other end of each spring 100 is formed to receive and bear against a respective small lug 102 on the trip bar 39.

Each sleeve 98 is threaded on an armature rod 104 having an armature 106 rigidly secured thereto between a pair of collars 107. The lower end portion of each armature rod 104 is reciprocally received in an eyelet 108 secured in the respective terminal strap 66. Upon a severe overload, each armature 106 is attracted into engagement with a U-shaped core member, only the bight portion 110 of which is shown. Each core member is secured beneath its respective terminal strap 66, and this leg portion thereof straddles the associated one of the terminal straps 66. Thus, the amount of current flowing in each terminal strap 66 determines the magnitude of the magnetic pull by the associated core on its associated armature 106.

The common trip bar 39 is provided with three pairs of lugs 114, each pair straddling one of the armature rods 104, so that upon the attraction of each armature 106 by its associated core 110, the associated sleeve 98 engages a pair of the lugs 114 to pivot the common trip bar 39 clockwise thereby to trip the circuit breaker as described in Patent No. 3,341,791. The tension springs 99 are respectively secured to bias the armatures 106 away from the respective cores.

In accordance with this invention, the bracket 94 for the outer :pole shown in FIG. 2 has an upper portion 120 extending perpendicular to the barrier 92 and is provided with an opening loosely receiving a cylindrical push-to-test pin 122 preferably molded from insulating material and having'a collar 124. An upper end portion 126above the collar extends loosely part way into an opening 128 in the cover 21 as a result of the bias of a helical spring 130 surrounding the pin 122 between the upper surface of the bracket portion 120 and the collar 124. A lower end face 126 of the pin 122, when the pin is in the normal extended position shown in FIGS. 3 and 5, is spaced a short distance above a lug 127 on the crossbar 39, and an u-pper end face 130 of the pin 122 is positioned materially below the upper surface of the cover 21 so that the pin 122 can be removed inwardly only by use of a tool smaller than the opening 128 in the cover 21. The opening 128 is too small for entry of a human finger.

When it is desired to trip the circuit breaker for test purposes, a pointed tool is inserted into the opening 128 to depress the pin 122 so that its lower end face 126 engages the lug 127 causing clockwise rotation of the trip bar 39. Such rotation of the trip bar 39 releases the latch mechanism of the circuit breaker as explained hereinbefore and in detail in Patent No. 3,341,791.

The terms upper, lower, top, bottom, rear, etc., as used herein and in the appended claims are purely relative, it being understood that the circuit breaker of the invention may be mounted in various positions.

We claim:

1. A molded-case circuit breaker comprising a molded case, a pair of separable contacts in the case, releasable means in the case normally restraining the contacts in an engaged position and releasable to effect separation of the contacts, a current-responsive trip mechanism in the case for releasing the releasable means upon flow of an excessive current through the current-responsive trip mechanism, the current-responsive trip mechanism including means movable to effect said release of the releasable means, a relatively small opening in the case, a pin mounted in the case for rectilinear movement and having an outer end portion extending into said opening from inside the case, a spring biasing the pin into said opening into an extended position in which the outer end portion of the pin extends into said opening for a distance less than the thickness of the case so that the outer end face of the pin is disposed inwardly of the outer surface of said case about said opening, a stop on the pin restraining the pin in the extended position against the bias of the spring, and the pin having its inner end face spaced from the movable means and arranged to engage and move the movable means, upon inward rectilinear movement of the pin, to effect said release of the releasable means.

2. A circuit breaker as claimed in claim 1 wherein the movable means includes a trip bar mounted Within the case to pivot about a pivot axis and having a radially extending lug thereon aligned to lie within the path of said rectilinear movement, which path is substantially perpendicular to and offset from said pivot axis, and the inner end face of the pin is in spaced-apart relation to the lug so that, upon inward rectilinear movement of the pin, the inner face engages the lug to pivot the trip bar thus effecting the release of the movable means.

3. A molded-case circuit breaker comprising a molded case, a pair of separable contacts in the case, releasa-bly latchable means in the case normally in a latched position retaining the contacts in engagement and releasable for movement to an unlatched position to effect separation of the contacts, a current-responsive trip mechanism in the case for releasing the releasably latchable means upon flow of an excessive current through the currentresponsive trip mechanism, the current-responsive trip mechanism including means movable to effect the release of the releasably latchable means, the movable means normally retaining the releasably latchable means in the latched position, a relatively small opening in the case, a pin mounted in the case for rectilinear movement and having an outer end portion extending into the opening from inside the case, a spring biasing the pin toward an outer position, and a stop on the pin cooperable with the case to retain the pin in the outer position against the bias of the spring, the pin having an inner end face engageable with the movable means only when an outer end face of the pin is disposed inwardly of the outer surface of the case defining the opening, and the movable means being moved to effect the release of the releasably latchable means upon rectilinear movement of the pin to a position wherein the outer end face thereof is disposed further inwardly of the outer surface of the case defining the opening.

References Cited UNITED STATES PATENTS 3,073,925 1/1963 Thomas 335-42 3,143,627 8/1964 Kiesel. 3,345,591 10/1967 Leonard 335-23 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner U.S. C1. X.R.

3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3 180,690 Dated Novemoer 25, lye;

Inventor) Beryl w Layt 1n and Rooer't w. Dunham It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

F Cu Lumn l, line 51;, "oil." should be or Column 2, line 20 "uuter" 0111i tted Deidre end line 37, "one" should be use Column 5, Line 20, "removed" should we moved SIGNED KND SEALED MAY 5 197 (SEAL) Attest:

Edward M. Fletcher, Ir. WILLIAM E- S-GHUYLER. J'R.

commissioner of EM Attesting Officer 

